1. Field of the Invention
The invention relates to a method for testing the transmission states of a device for wireless communication in a radio network.
2. Discussion of the Background
Digital mobile radio devices and also other devices for wireless communication are becoming ever more complex and increasingly have at their disposal transmission parameters which can be adapted to the transmission quality and which enable a plurality of transmission states merely by reason of practical combinations thereof. Examples of such transmission parameters of the transmission signal are power, modulation type, various types of multiplexing, the use of various antennas in Multiple Input Multiple Output (MIMO) systems etc. The transmission quality describes the quality of the physical transmission on the transmission path. The transmission state which is to be adjusted is selected by means of an item or items of decision information, e.g. of a measured transmission quality, which is/are transmitted by the mobile radio device. New transmission standards allow a mobile telephone to transmit a recommendation for a transmission state, which is to be adjusted, to the base station which is able to accept or reject this recommendation according to the capacity utilization thereof.
For the development of devices which in all operating situations adjust or recommend the correct transmission state, it is very useful to examine the switching procedures between two transmission states. However, classic testing methods test only the transmission rate in dependence upon the transmission quality, in that the transmission rate is measured at a constantly improved transmission quality, as illustrated in FIG. 1. The prior art testing methods are characterized by various functions of the transmission quality over time, in order to simulate fluctuations in channel quality, as occur in reality. Therefore, e.g. fading oscillations are simulated in the German patent specification DE 100 25 838 B4 by a Monte Carlo method.
Classic tests of this kind do not enable the developer to gain any knowledge relating to the switching procedures, i.e. the decision relating to the transmission state of the mobile radio device to be tested.
Not only are the switching points not known, they are also not clearly defined. The decision relating to the switch between two transmission states includes a hysteresis effect, in order to prevent the transmission state from changing constantly at the switching point and in proximity thereto.
In addition, there are still no testing methods which test mobile radio devices of modern transmission standards which provide recommendations of a transmission state to the base station. An examination of the switching points between suggestions of various transmission states is therefore of particular interest for the development of this new generation of mobile radio devices.
Similar problems occur during the testing of base stations which decide the transmission state, which is to be adjusted, on the basis of return values of the mobile radio device and thus produce switching procedures. Classic return values thus specify the transmission quality, whereas in more recent transmission standards such as e.g. WiMAX (Worldwide Interoperability for Microwave Access) recommendations of a transmission state, which is to be adjusted, are also transmitted as return values to the base station. In this application, return values are defined as the decision information which is transmitted by a mobile radio unit to a base station and which is relevant for the decision of the base station for a transmission state to be adjusted subsequently.